Furnace hearth



J. F. JORDAN FURNACE HEARTH July 11, 1950 Filed May 3, 1947 WWW/ AMJAA contacting liquid.

Patented July 11, 1950 FURNACE HEARTH J ames Fernando Jordan, Huntington Park, Calif., assignor to Jordan Research Laboratory, Inc., Huntington Park, I Calif., acorporation of Nevada I Application May 3, 1947, Serial No. 745,854

1 Claim.

My invention relates to the hearth of my continuous refining furnace, Serial No. 578,742 filed on Feb. 19, 1945, later abandoned.

My objective concerns an improvement in the operating characteristics of the hearth of my furnace.

Figure 1 shows asection of the hearth of my furnace, with thethermaldams located along, and within, the hearth.

Figure 2 shows section Figure 1. Y .5 i l Due to the fact that my. furnace is a continuous furnace, the refractories which constitute the hearth are not subjected tothe rather drastic thermal shocks which. the hearths in ordinary batch-type'furnaces are subjected. In spite of this improved refractory situation, however, ,the

A-AA, indicated in l refractories which constitute the hearth in my continuous furnace may be expected to suffer erosion by, themetallurgical liquid that lies in con- As the hearthof my furnace erodes, the erosion may be expected to take the form of elongated channels or grooves, with their longitudinal axis lying parallel to the direction of flow of the In an ordinary, batch-type metallurgical furnace, the actual shape or form that the erosion takes does not necessarily have a bearing on the outcome of the reactions being carried out within the furnace; butin my con-- tinuous furnace, the development of longitudinal channels along; the hearth will quickly lead to a serious breakdown in the refining action.

My furnace is a metallurgical reaction vessel wherein the reactants arebrought into turbulent contact with each other by superimposing a flowing filament of one reactantupon a flowing filament of another reactant,fas both reactants flow in a substantially horizontal manner through the furnace. The principal-flow direction'of the liquids being longitudinal, themolten reactant metal lying in any given longitudinal plane of the metal bath must depen'd upon the reactant power of the molten reagent slag that lies within this selfsame longitudinal plane; Thus, little dependence can be placed upon any appreciable movement of the reactant liquids in a plane that lies transverse to the flow direction.

Inasmuch as economy dictates thatno more reagent be employed than necessary, it follows so-called ghost excesses.

and showed the importance of the "ghost excesses to the smooth operation of the unit.

Serial No. 688,927 depended for its novelty on the uniform composition of the advancing transverse reactant filaments, that is, the chemical composition of any transverse cross section of the reacting liquids must exhibit a substantially uniform character. If this were not so, it would not be possible to accurately define such phenomena as the zone of reaction, the planes of completion, or the zones of excess reagent; furthermore, without uniform transverse reaction fronts, these thin-layer furnaces become metallurgically useless.

1 Assuming everything else to be equal, transverse uniformity is predicated upon the maintenance of a uniform depth of the reactant liquids.

. It will be understood that the upper liquid is of uniform depth in all cases, and that depth irregularities will be found only in the lower liquid layer. Naturally, depth irregularities in this lower layer can only result from irregularities in the surface of the furnace hearth.

For the sake of illustration, assume that any ,given metallurgical reaction between an impure metal and a reagent slag is proceeding normally within a counter-current unit of my refining furnace. With the layer depths and all other operating features uniform, thetransverse composition of either liquid, at any given transverse secvelop in the hearth of the furnace within the zone of reaction. The reaction rate in the longitudinalsection of the bath that is defined by the transverse diameter of this eroded hole will be below the normal reaction rate-for the simple reason that the hole increases the diffusion distance in the reaction area immediately thereover. The immediate result of this decreased reaction rate will be a projection of the planes of completion into the zones of excess in the plane defined by the holes transverse diameter. This projection will not be, in itself, of serious concern to the operation unless theprojection proceeds far nelling tendency of the hearth.

' maximum and minimum distances.

must not be so far from surface I9 that the coolenough to throw the planes out of the furnace. This protection that the zones of excess give the operation against such simple breakdowns as hearth holes, serves to stress the importance of the novelties disclosed in m Serial No. 688,927.

But now assume that this simple round hole is slowly eroded into a longitudinal channel whose axis lies parallel to the direction of flow. All along this channel the reaction is inhibited and delayed by the increased diffusion distance, and, as the erosion continues, it is certain that :the planes of completion are to be projected out of the furnace-a result that signals aserious brea'kdown in the operation.

To summarize: hearth holesneednotbe of =immediate concern to the operating characteristics of the furnace, but longitudinal channels will cause a, breakdown in the refining action.

Unfort inately, longitudinal channeling is a natural phenomenon connected with the flow of an erosive liquid. Thus, even if the erosion were to first evidence itself as 'a small round hearth "hole, subsequent action of the flowing liquid against the hole would likely result in the formation of a longitudinal channel.

I have discovered a method of building the refractory hearth in my continuous refining fursupported by shell I5. Interacting liquids l2 and I3 are shown flowing along and by surface I9, which surface I9 is the principal subject of my invention being herein disclosed. Embedded beneath surface iii are a series of water pipes I9. Pipes I9 all he at right angles to the direction of flow of liquids I2 and I 3, and are all equidistant from, and parallel to, reaction interface II.

Figure 2 shows section A-AA, indicated in Figure 1. Here, pipe I9 is shown to pass entirely through the body of the furnace. Pipe I carries cooling-water II, and discharges waste-water I8. Pipes Ii) should be spaced from each other at frequent enough intervals to break up the chan- In the ordinary case, a space between pipes Ill of from 2 to 12 inches will be suitable. In general, the more erosive the conditions are at surface IS, the closer pipes I!) must be spaced in order to break up channelling.

The distance that pipes It! must be buried beneath surface I9 may be defined by stating the Pipes I9 in effect of each pipe In is not demonstrated by the fact that the surface I9 that is immediately over each pipe I e is cooler than the surface I9 that is not thereover. Pipes II) should not be any closer to surface I9 than may be achieved without actually causing the cooling effect to interfere with the flow system that constitutes this refining method. Under normal conditions, pipes -l i: will be buried with their upper edge from 1 to 3 inches below surf-ace I9.

lhe refractory ram-mixture that surrounds ing-effect of water I'I,*as it passes through pipes I 9, creates narrow strips of surface I9 that are somewhat cooler than surface I9 as a whole.

These narrow, cooled strips lie at right angles to the direction of flow of liquids I2 and I3. While erosion may *take place between these cooled s'trips inythe usual way, when the erosive action -meets one-of thehooled strips (hereinafter called,

"thermal dams to erosion is occasioned by the increased hardness exhibited by cooler refractories; and bythe verysteep temperature gradient in the refractory lying over pipes Ill. 'Thus, as the eroding liquid 'penetrates into the hearth at the locale of the thermal dams, it immediately meets surf-aces which are' cooledso much that the eroding liquid is strongly handicapped by becoming viscous--and may, in fact, actually solidify. In any case, the creation of longitudinal channels is stopped by the thermal dams.

The strengthof the thermal dams may be varied by varying the distance between pipes I0 and surface "I9, and by =varying the amount of water that'is passing thru pipes ID.

'I claim as my invention:

In a continuous refining furnace wherein a horizontally-flowing"stream of molten metal is beingrefined by a 'horizontally flowing stream of molten slag that'is floating on and in-contact with said stream of molten metal, the method of preventing the erosion of'the hearth of said furnace from interfering with "said refining operation, which comprises: burying a series of substantially parallel pipes beneath 'the surface of said hearth, each 'of "said pipes being substantially parallel to and at a substantially equal distance from said surface and substantially at right angles to the direction of flow of said stream of molten'metal through said furnace; and circulating water through said buried pipes, so as to cool strips of said surface, so as to prevent said metal stream from eroding longitudinal channels in said hearth.

JAMES -FERNANDO JORDAN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date "548,496 .Ames 'Oct..22, 1895 2,190,271 Powell Feb. .13, 1940 FOREIGN PATENTS Number Country Date 3,137 Great Britain 1868 588,772 Germany Nov. 30, 1933 

